Project Summary/Abstract Alcohol Use Disorder (AUD) is a widespread problem with significant health and societal consequences and a need for improved treatments. The endogenous cannabinoid system is a promising target for new AUD pharmacotherapy. Prolonged ethanol consumption leads to molecular and epigenetic changes in the amygdala underlying the negative affective state in addiction. The amygdala has a high density of cannabinoid CB1 receptors. While cannabinoid antagonists reduce ethanol drinking, their ability to alter molecular and epigenetic changes in the amygdala remains unexplored. Furthermore, neutral cannabinoid receptor antagonists possess less psychiatric liabilities than older inverse agonists such as rimonabant. This project exploring cannabinoid receptor manipulations will provide evidence for a novel AUD pharmacotherapy and characterize the epigenetic regulation of the endocannabinoid system in drinking behaviors. Despite indications neutral cannabinoid receptor antagonism reduces drug and ethanol consumption, it is less clear how chronic ethanol drinking epigenetically impacts the endocannabinoid system or how CB1 receptors in specific addiction-related brain circuits such as the extended amygdala regulate drinking behaviors. This proposal is based on the hypothesis that modulation of the CB1 receptor system can reduce escalated ethanol drinking and reverse alcohol-induced changes in gene expression and histone modifications in the amygdala. We will test this hypothesis by assessing AM4113 effects on drinking behavior and biochemical changes in amygdalar endocannabinoid system gene expression and global and specific Cnr1 (CB1 mRNA) histone modifications following intermittent-access 20% ethanol drinking. We will further test the effect of Cnr1 knockdown within the central and basolateral nuclei of the amygdala on protracted drinking behavior to specifically localize sub-regions of the amygdala as sufficient for these same downstream behavioral and biochemical effects. Overall, these experiments will further the understanding of the endocannabinoid system and its epigenetic regulation during protracted ethanol drinking while providing key preclinical data for translating endocannabinoid-targeted treatments for AUD.